In 1972 we have presented evidence for the existence of an insulin sensitive center in the central nervous system (CNS). Selective regional insulinization of the CNS through the carotid artery in anesthetized rats resulted in reduction of the systemic blood sugar in healthy as well as in experimental diabetic animals, presumably by inhigition of the hepatic glucose production. The objectives of the current research project are: 1). To elucidate the hormonal or neural pathway(s) which transmit the impulses from the insulin sensitive CNS glucoregulator center to regulate hepatic metabolism, 2). To localize the center within the CNS, 3). To identify the mechanism of action of the insulin sensitive chemoreceptor(s) within the evidenced glucoregulator center, 4). To study the behaviour of the chemoreceptor(s) in experimental conditions resembling human disease states, such as obesity, hyperinsulinemia, growth hormone excess and diabetes mellitus. It is hoped, that these studies will contribute toward the understanding of a previously unsuspected action of insulin on carbohydrate metabolism, mediated thrugh the CNS. As this is an extremely sensitive, very rapid action, its investigation may be of importance far beyond academic interest, inasmuch it may yield clues to the initial metabolic errors which lead to important disease states, such as obesity, hyperinsulinism and diabetes mellitus.